U.S. patent application number 11/414329 was filed with the patent office on 2006-11-23 for doctor blade and development unit having the same.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Young-min Kim, Joo-hwan Noh.
Application Number | 20060263117 11/414329 |
Document ID | / |
Family ID | 37448409 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060263117 |
Kind Code |
A1 |
Kim; Young-min ; et
al. |
November 23, 2006 |
Doctor blade and development unit having the same
Abstract
A doctor blade and a development unit having the same are
disclosed. The doctor blade includes: an elastic blade having one
edge contacting a developer roller with a predetermined pressure to
control a toner layer formed on the developer roller; and a
supporting member supporting the other edge portion of the elastic
blade, wherein a middle portion of the supporting member is larger
than each end portion of the supporting member. Accordingly,
contact pressure between the elastic blade and the developer roller
is uniformly distributed along a length direction of the elastic
blade.
Inventors: |
Kim; Young-min; (Suwon-si,
KR) ; Noh; Joo-hwan; (Yongin-si, KR) |
Correspondence
Address: |
STEIN, MCEWEN & BUI, LLP
1400 EYE STREET, NW
SUITE 300
WASHINGTON
DC
20005
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
Suwon-si
KR
|
Family ID: |
37448409 |
Appl. No.: |
11/414329 |
Filed: |
May 1, 2006 |
Current U.S.
Class: |
399/284 |
Current CPC
Class: |
G03G 15/0812 20130101;
G03G 2215/0866 20130101 |
Class at
Publication: |
399/284 |
International
Class: |
G03G 15/08 20060101
G03G015/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2005 |
KR |
2005-43038 |
Claims
1. A doctor blade of an image forming apparatus comprising: an
elastic blade having a first edge contacting a developer roller
with a predetermined pressure to control a toner layer formed on
the developer roller; and a supporting member supporting a second
edge of the elastic blade, wherein a size of a middle portion of
the supporting member is larger than a size of each end portion of
the supporting member.
2. The doctor blade of claim 1, wherein a width W1 of the middle
portion of the supporting member is larger than widths W2 and W3 of
the respective end portions of the supporting member.
3. The doctor blade of claim 2, wherein the middle portion of the
supporting member is projected along the elastic blade toward the
first edge of the elastic blade a predetermined amount farther than
both end portions of the supporting member.
4. The doctor blade of claim 3, wherein the projected portion of
the middle portion of the supporting member forms a curved line
shaped edge.
5. The doctor blade of claim 3, wherein the projected portion of
the middle portion of the supporting member forms a straight line
shaped edge.
6. The doctor blade of claim 3, wherein the projected portion of
the middle portion of the supporting member forms a nonlinear
shaped edge.
7. The doctor blade of claim 4, wherein a projected distance of the
projected portion is set less than 40% of a distance L measured
from ends of the supporting member to the first edge of the elastic
blade.
8. The doctor blade of claim 7, wherein the projected distance of
the projected portion is about 20% of the distance L.
9. The doctor blade of claim 5, wherein a projected distance of the
projected portion is set less than 40% of a distance L measured
from ends of the supporting member to the first edge of the elastic
blade.
10. The doctor blade of claim 9, wherein the projected distance of
the projected portion is about 20% of the distance L.
11. A doctor blade of an image forming apparatus comprising: an
elastic blade having a first edge contacting a rotating developer
roller with a predetermined pressure to control a thickness of a
toner layer on the developer roller; a supporting member supporting
a second edge of the elastic blade; and seal members respectively
mounted on each end of the elastic blade to prevent leakage of a
toner, wherein a size of a middle portion of the supporting member
is larger than a size of each end portion of the supporting member
to uniformly distribute contact pressure between the elastic blade
and the developer roller throughout a length direction of the
elastic blade.
12. The doctor blade of claim 11, wherein the middle portion of the
supporting member is projected along the elastic blade toward the
first edge of the elastic blade by a predetermined distance.
13. The doctor blade of claim 12, wherein the projected portion of
the supporting member forms a curved line shaped edge.
14. The doctor blade of claim 12, wherein the projected portion of
the supporting member forms a straight line shaped edge.
15. The doctor blade of claim 12, wherein the projected portion of
the middle portion of the supporting member forms a nonlinear
shaped edge.
16. The doctor blade of claim 13, wherein the projected portion is
projected less than 40% of a distance L measured from ends of the
end portions of the supporting member to the first edge of the
elastic blade.
17. The doctor blade of claim 16, wherein the projected distance of
the projected portion is about 20% of the distance L.
18. The doctor blade of claim 15, wherein the projected distance of
the projected portion is less than 40% of a distance L measured
from ends of the end portions of the supporting member to the first
edge of the elastic blade.
19. The doctor blade of claim 18, wherein the projected distance of
the projected portion is about 20% of the distance L.
20. A development unit comprising: a developer roller rotatably
arranged to face a photoconductor; an elastic blade having a first
edge contacting the rotating developer roller to control a
thickness of a toner layer of the developer roller; a supporting
member supporting a second edge of the elastic blade; and seal
members respectively mounted at each end of the elastic blade to
prevent leakage of a toner, wherein the elastic blade is fixed to
the supporting member to have uniform contact pressure between the
elastic blade and the developer roller along a length of the
developer roller.
21. The development unit of claim 20, wherein the supporting member
has a middle portion having a larger size than both end
portions.
22. The development unit of claim 21, wherein the middle portion of
the supporting member is projected toward the first edge of the
elastic blade farther than both end portions of the supporting
member.
23. The development unit of claim 22, wherein the projected portion
of the supporting member forms a curved line shaped edge.
24. The development unit of claim 22, wherein the projected portion
of the supporting member forms a straight line shaped edge.
25. The development unit of claim 22, wherein the projected portion
of the supporting member forms a nonlinear shaped edge.
26. The development unit of claim 23, wherein the projected portion
is projected a distance less than 40% of a distance L measured from
ends of the supporting member to the first edge of the elastic
blade.
27. The development unit of claim 26, wherein the projected portion
is projected a distance about 20% of the distance L.
28. The development unit of claim 24, wherein the projected portion
is projected a distance less than 40% of a distance L measured from
ends of the supporting member to the first edge of the elastic
blade.
29. The development unit of claim 28, wherein the projected portion
is projected a distance about 20% of the distance L.
30. The development unit of claim 20, wherein the supporting member
and the elastic blade are adhered by a weld.
31. The development unit of claim 20, wherein the supporting member
and the elastic blade are adhered by an adhesive.
32. The development unit of claim 20, wherein the supporting member
and the elastic blade are joined by a fastener.
33. A doctor blade of an image forming apparatus comprising: an
elastic blade having a first edge contacting a developer roller
with a predetermined pressure to control a toner layer formed on
the developer roller; and a supporting member supporting a second
edge of the elastic blade, wherein the elastic blade is fixed to
the supporting member to have uniform contact pressure between the
elastic blade and the developer roller along a length of the
developer roller.
34. The doctor blade of claim 33, wherein an edge of the supporting
member projected long the elastic blade toward the developer roller
forms a nonlinear shaped edge.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Patent
Application No. 2005-43038, filed May 23, 2005, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Aspects of the present invention relate to a doctor blade
and a development unit using the same in an electro-photographic
type image forming apparatus such as a printer, a copier or a
facsimile.
[0004] 2. Description of the Related Art
[0005] An electro-photographic type image forming apparatus forms
an image on a print medium, such as a paper, when a signal such as
a video signal is received from a host, such as a computer. In
order to form the image on the print medium, the
electro-photographic type image forming apparatus irradiates a
laser beam on a photoconductor according to the video signal to
form an electrostatic latent image on the photoconductor. The
electrostatic latent image is developed using a toner to form a
toner image, and the toner image is transferred to a surface of the
print medium. Finally, the electro-photographic type image forming
apparatus outputs the print medium with the image formed
thereon.
[0006] FIG. 1 shows a development unit according to the related
art.
[0007] Referring to FIG. 1, the development unit includes: a
photoconductor 1; a developer roller 2; and a doctor blade 10. The
developer roller 2 is rotatably disposed to face the photoconductor
1. The doctor blade 10 forms a toner layer with a constant
thickness on the developer roller 2 by controlling a thickness of
toner supplied to the developer roller 2. The doctor blade 10
adheres closely to the developer roller 2 to control the thickness
of toner applied to the developer roller 2. Ordinarily, the toner
in a toner cartridge is supplied to the developer roller 2 by a
toner supply roller (not shown).
[0008] FIG. 2 shows another view of the doctor blade 10 shown in
FIG. 1.
[0009] As shown in FIG. 2, the doctor blade 10 includes a
supporting member 11 having a predetermined width and length; an
elastic blade 12 having one edge portion fixed to the supporting
member 11 and the other edge portion elastically contacted to the
developer roller 2; and seal members 13, 13' arranged at each end
of the elastic blade 12. The supporting member 11 adheres to a
development unit frame (not shown), and the elastic blade 12 is
connected to the supporting member 11 by an adhesive or weld.
[0010] Such a doctor blade 10 is designed to uniformly distribute a
contact pressure of the elastic blade 12 along the entire length of
the developer roller 2. If the contact pressure is not uniformly
distributed, the toner will not be uniformly distributed, that is,
the toner will be supplied on the developer roller 2 with neither a
constant electric potential nor a constant thickness. As a result,
concentration of toner across an image formed on the print medium
becomes uneven giving the image an unintended partially washed-out
and/or partially bolded appearance.
[0011] Although the doctor blade 10 is designed to uniformly
distribute the contact pressure, according to the related art, the
doctor blade 10 produces a non-uniform contact pressure
distribution (A) between the developer roller 2 and the elastic
blade 12 because of added pressure on the elastic blade 12 from the
seal members 13, 13' which are mounted at each end of the elastic
blade 12 to prevent leakage of the toner as shown in FIG. 2. More
specifically, the seal members 13, 13' are supported by the
development unit frame (not shown), and the seal members 13, 13'
bear down on each respective end of the elastic blade 12, thus
exerting an additional pressure on both ends of the elastic blade
12. Accordingly, the contact pressure on both end portions of the
elastic blade 12 becomes greater than on a middle portion of the
elastic blade 12. Therefore, images may be lightly formed on a left
side and a right side of the print medium due to lighter
concentrations of toner in these areas because the thickness of the
toner layer formed on the end portions of the developer roller 2 is
overly limited by the additional pressure from the seal members 13,
13'. Further, since images are normally formed on the middle
portion of the print medium, this is where the target toner
concentration or image contrast is set, thus the additional
pressure on the elastic blade 12 from the seal members 13, 13'
typically results in printed images having washed-out side
portions. In other words, the non-uniform distribution of contact
pressure A causes an uneven toner distribution on the developer
roller 2 and a corresponding image concentration, i.e., contrast,
problem in the printed images.
SUMMARY OF THE INVENTION
[0012] Accordingly, aspects of the present invention provide a
solution to the above-mentioned and/or other problems, among other
benefits. An aspect of the present invention provides a doctor
blade of an image forming apparatus to uniformly maintain a contact
pressure between an elastic blade and a developer roller to resolve
uneven image concentration problems.
[0013] Additional aspects and/or advantages of the invention will
be set forth in part in the description which follows and, in part,
will be obvious from the description, or may be learned by practice
of the invention.
[0014] An aspect of the present invention provides a development
unit having the doctor blade to uniformly maintain a contact
pressure between an elastic blade and a developer roller to resolve
uneven image concentration problems and improve image quality.
[0015] In accordance with an aspect of the present invention, there
is provided a doctor blade of an image forming apparatus including:
an elastic blade having one edge portion in contact with a
developer roller with a predetermined pressure to control a toner
layer formed on the developer roller; and a supporting member
supporting the other edge portion of the elastic blade, wherein a
size of a middle portion of the supporting member is larger than
the size of each end portion of the supporting member.
[0016] According to an aspect of the present invention, the
supporting member may be divided into three portions in a length
direction, which are the two end portions and the middle portion,
where the size of the middle portion of the supporting member is
larger than the size of each end portion of the supporting
member.
[0017] According to an aspect of the present invention, the width
of the middle portion of the supporting member may be greater than
the width of each end portion of the supporting member. The middle
portion of the supporting member may project or protrude along the
elastic blade farther than both end portions of the supporting
member by a predetermined distance. The projected middle portion of
the supporting member may form as a curved-line or a straight-line
shaped edge. The additional width of the projected portion may be
set less than 40% of a distance L, where L is the distance from an
end portion of the supporting member to the contact edge portion of
the elastic blade, and the additional width of the projected
portion may be about 20% of the distance L.
[0018] Another aspect of the present invention provides, a doctor
blade of an image forming apparatus including: an elastic blade
having one edge portion in contact with a rotating developer roller
with a predetermined pressure to control a thickness of a toner
layer on the developer roller; a supporting member supporting the
other edge portion of the elastic member; and a seal member mounted
on each end of the elastic blade to prevent leakage of the toner,
wherein the size of the middle portion of the supporting member is
larger than a size of each end portion of the supporting member to
uniformly distribute contact pressure between the elastic blade and
the developer roller along a length direction of the developer
roller.
[0019] According to an aspect of the present invention, there is
provided a development unit including: a developer roller rotatably
arranged to face a photoconductor; an elastic blade having one edge
portion in contact with the rotating developer roller to control a
thickness of a toner layer on the developer roller; a supporting
member supporting the other edge portion of the elastic blade,
wherein one side of a middle portion of the supporting member may
protrude along the elastic blade farther than each end portion of
the supporting member by a predetermined distance to exert a higher
elastic stress in the elastic blade along the middle portion to
cause the contact pressure between the elastic blade and the
developer roller to be uniform along the length of the developer
roller; and seal members respectively mounted at each end of the
elastic blade to prevent leakage of the toner.
[0020] According to an aspect of the present invention, the
supporting member has a middle portion having a larger size than
both end portions. According to an aspect of the present invention,
the width of the middle portion of the supporting member may be
larger than the widths of the end portions of the supporting
member. The additional width of the middle portion of the
supporting member may be projected along the elastic blade farther
than both end portions of the supporting member. The projected
portion of the supporting member may form a curved-line or a
straight-line shaped edge. The additional width of the projected
portion may be projected less than 40% of a distance L measured
from an end portion of the supporting member to the edge of the
elastic blade contacting the developer roller, and the additional
width may be about 20% of the distance L.
[0021] According to an aspect of the present invention, the
supporting member and the elastic blade are joined by an adhesive,
a weld or a fastener.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] These and/or other aspects and advantages of the invention
will become apparent and more readily appreciated from the
following description of the embodiments, taken in conjunction with
the accompanying drawings of which:
[0023] FIG. 1 is a schematic view illustrating a development unit
with a doctor blade according to the related art;
[0024] FIG. 2 is a view showing a contact pressure distribution A
between an elastic blade and a developer roller shown in FIG.
1;
[0025] FIG. 3 is a schematic view depicting a development unit
having a doctor blade according to an embodiment of the present
invention;
[0026] FIG. 4 shows a contact pressure distribution B between an
elastic blade and a developer roller shown in FIG. 3; and
[0027] FIG. 5 shows a doctor blade and contact pressure
distribution B according to another embodiment of the present
invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] Reference will now be made in detail to the present
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings, wherein like reference
numerals refer to the like elements throughout. The embodiments are
described below in order to explain the present invention by
referring to the figures.
[0029] The matters defined in the description such as a detailed
construction and elements are nothing more than that needed to
assist in a comprehensive understanding of the invention. Thus, it
is apparent that the present invention can be carried out without
these defined matters. Also, well-known functions or constructions
to one of skill in the art are not described in detail since they
would obscure the invention in unnecessary detail.
[0030] FIG. 3 is a schematic view depicting a development unit
having a doctor blade according to an embodiment of the present
invention, and FIG. 4 shows a contact pressure distribution between
an elastic blade and a developer roller shown in FIG. 3.
[0031] Referring to FIGS. 3 and 4, a laser beam is irradiated
according to a signal from a laser scanning unit 220 on a
photoconductor 210 to form a predetermined electrostatic latent
image on the photoconductor 210. A developer roller 230 supplies a
toner to the photoconductor 210 to develop the electrostatic latent
image, and the developed toner image is transferred onto a print
medium P which travels between the photoconductor 210 and a
transfer roller 240. As shown in FIG. 3, the development unit also
includes: a toner supply roller 250 for supplying the toner in a
toner case 260; an agitator 270, a cleaning roller 280, and a
cleaning blade 290. As described above, the doctor blade 100
controls the thickness of the toner supplied from the toner supply
roller 250 to the developer roller 230 to form a toner layer with a
constant thickness on the developer roller 230. As shown in FIG. 4,
the doctor blade 100 includes a supporting member 110, an elastic
blade 120 and a pair of seal members 130 and 130'.
[0032] The supporting member 110 according to the present
embodiment is designed to have a middle portion S1 having a larger
size than both side portions S2 and S3. This is because each seal
member 130, 130' exerts additional pressurize on its respective end
of the elastic blade 120 which causes an increase in the elastic
stress in the elastic blade 120 at the ends and a corresponding
increase in the contact pressure at both ends of the elastic blade
120. The larger middle portion S1 of the supporting member 110
increases the elastic stress of the middle portion of the elastic
blade 120 to uniformly distribute the contact pressure along the
entire length of the contact between the elastic blade 120 and the
developer roller 230.
[0033] As described above, in the present embodiment the width W1
of the middle portion S1 of the supporting member 110 is wider by a
predetermined amount than the width W2 of the end portions S2 and
S3 of the supporting member 110. In more detail, the middle portion
S1 of the supporting member 110 is projected farther along the
elastic blade 120 toward a contact edge 121 of the elastic blade
120 by a distance "a" compared to the end portions S2 and S3 of the
supporting member 110. Thus decreasing a distance from the middle
portion S1 projected edge 111 to the contact edge 121 to increase
the contact pressure of the middle portion of the elastic blade
120.
[0034] The projected edge 111 of the supporting member 110
increases the contact pressure of the middle portion of the elastic
blade 120 by an amount equivalent to the increase in contact
pressure of the end portions of the elastic blade 120 due to
pressure exerted by the seal members 130 and 130'. Accordingly, a
uniform contact pressure distribution B is obtained. Herein, the
entire contact pressure can be properly set by controlling a
distance and an angle between the developer roller 230 and the
elastic blade 120.
[0035] The projected portion edge 111 of the supporting member 110
may be formed as a curved line shape or a straight line shape as
shown in FIG. 5. FIG. 5 shows a doctor blade 100' according to
another embodiment of the present invention. In FIG. 5, the edge
closest to the developer roller 230 at each end of the supporting
member 110' is tapered. As shown in FIG. 5, the supporting member
110' has a projected middle portion S1 to increase the contact
pressure of the middle portion of the elastic blade 120.
Accordingly, the contact pressure is uniformly distributed along
the length of the developer roller 230. That is, a uniform
distribution B of the contact pressure is obtained.
[0036] In embodiments of the present invention, the edge of the
projected portion 111 of the supporting member 110 is formed as a
curved line shape and a straight line shape as shown in FIGS. 4 and
5. However, the present invention is not limited thereby. That is,
the projected portion of the supporting member 110 according to the
present invention can be formed as any shape to increase a
dimension of the middle portion S1 of the supporting member to
increase the contact pressure of the middle portion of the elastic
blade 120 and to thus adjust the contact pressure distribution to
achieve uniform contact pressure with the developer roller.
[0037] In addition, the present invention is not limited to a
particular projected length "a" of the middle portion S1 of the
supporting member 110. Simulation results indicate that any
projected length "a" under 40% of a distance L, where L is measured
from a front edge of an end portion of the supporting member 110 to
the contact edge 121 of the elastic blade 120, is effective in
achieving a uniform contact pressure distribution Bw. If the length
of the projected portion "a" is longer than 40% of L, then too much
contact pressure is applied. Simulations indicate that 20% of the
distance L is preferred. For example, if the distance L is 10 mm,
the length "a" of the projected portion is about 2 mm.
[0038] The elastic blade 120 includes: a contact edge portion 121
in contact with the rotating developer roller 230 with a
predetermined pressure to control the thickness of the toner
supplied on the developer roller 230; and a base edge portion 122
fixed to the supporting member 110 with adhesive or a weld.
Spot-welding may be performed to join the supporting member 110 and
the elastic blade 120. A general spot welder can be used since the
joining is along a linear contact line between the supporting
member 110 and the base edge 122 of the elastic blade 120. That is,
since the spot-welding is performed along a linear line, no
specially manufactured welder is required. Specifically, welding is
not required along the shape of the projected edge 111 of the
middle portion S1 of the supporting member 110. Therefore, a
typical welder can be used.
[0039] Each of the seal members 130 and 130' is supported at the
toner case 260 and respectively located at each end of the elastic
blade 120. The seal members 130, 130' prevent the toner from
leaking past the ends of the elastic blade 120 as the elastic blade
120 controls the thickness of the toner layer formed on the
developer roller 230.
[0040] The seal members 130 and 130' cause the uneven toner
concentration problems in the printed images in the related art. A
beneficial aspect of the present invention is to overcome such a
drawback, by allowing the projected edge 111 of the middle portion
S1 of the supporting member 110 to project by a predetermined
length "a" along the elastic blade 120 toward the contact edge 121
to increase the contact pressure of the middle portion of the
elastic blade 120. Accordingly, in an embodiment of the present
invention, the contact pressure is uniformly distributed along the
elastic blade 120 and the developer roller 230 to resolve the
uneven toner concentration problem and improve the image
quality.
[0041] Although a few embodiments of the present invention have
been shown and described, it would be appreciated by those skilled
in the art that changes may be made in this embodiment without
departing from the principles and spirit of the invention, the
scope of which is defined in the claims and their equivalents.
* * * * *